1. Field of the Invention
The present invention is a tool for releasably attaching to sheets of material and applying a prying or pushing force.
2. Description of the Related Art
In pressure-vessel and storage-tank construction, large sheets of metal must often be positioned relative to each other for joining. Typically this joining is accomplished by welding the sheets of metal together. To properly weld the sheets of metal, however, they must be in proper alignment with each other.
Two common methods of joining sheets of metal are lap-joints and butt-joints. A lap-joint is where the ends of metal sheets overlap each other. Then the edge of each sheet is welded to the face of the other sheet. A butt-joint is where the two sheets are aligned edge-to-edge. Once the edges are properly aligned, they are welded together. Both of these methods of joining metal sheets require the edge of one sheet to align with the face or edge of the other sheet.
These methods of joining materials are used on a variety of materials, not just metals. For example, large sheets of plastic, fiberglass, wood, or other materials can be joined together using lap-joints and butt-joints. These non-metallic materials can be joined by plastic welding, special adhesives, and other means well known in the art. To properly join large sheets of these materials, the edge of one sheet must again align with the face or edge of the other sheet.
However, the sheets of materials typically do not align properly with each other. Variations in the construction and properties of the sheets to be joined often keep the edge of one sheet from closely following the face or edge of the other sheet. Those variations can result in the edge of one sheet being too far from the face or edge of the other sheet for the two to be properly joined. Thus, the areas for the lap-joint or butt-joint must be brought into closer alignment before joining can be carried out.
When dealing with large sheets of metal or other materials, the need to align the sheets poses a problem. Because of the size of the sheets, clamps are impractical and often impossible to use. A common c-clamp or bar clamp, will not work on large sheets because the jaws of the clamp cannot extend the several feet needed to reach to the center of the sheet. Thus large sheets of material must often be aligned and joined using complicated and time consuming processes.
For example, large metal sheets are often aligned using blank nuts, key-plates and bull-pins. This process requires a blank nut, which is a square block with a hole through the center. Two blank nuts are aligned and welded to each sheet of metal on opposite sides of the anticipated weld-line. Then a key-plate, which is a specially designed tool, is placed over the blank nuts. The key-plate is held in place on the blank nuts by inserting a bull pin through each blank nut such that it passes through the key-plate and blank nut. Then additional bull-pins are inserted between the key-plate and blank nuts to adjust the metal sheets relative to each other. These adjustments are carried out by using the bull pins and key-plate to push or pull on the blank nuts as needed to adjust the metal sheets. Once the metal sheets are properly aligned, the aligned area is secured typically by welding. After one area is secured, the bull-pins are removed, and the key-plate is lifted off. Then the blank nuts are removed by cutting the welds that hold the blank nuts in place and grinding those welds off the metal sheets. This grinding occasionally requires an additional inspection of the metal sheets to ensure that the welding, cutting, and grinding around the blank nuts did not cause unacceptable damage to the metal sheets.
The above process must be carried out at every location that a joint is needed. That often requires the process to be repeated several times to complete a complete lap-joint or butt-joint.
This method for joining metal sheets has several drawbacks. For example, it is time consuming. It can take workers several hours to complete the process of welding blank nuts into place, installing the key-plate and bull pins, aligning the sheets, welding the sheets, and removing the bull pins, the key-plate, and blank nuts.
An additional limitation of the above method is that it can damage the surface of the metal sheets that are joined. This occurs because the blank nuts must be welded into place and then removed by cutting. This leaves portions of a weld that must often be ground down to smooth out the surface. In some situations, the removal of the blank nuts and their welds requires the surface of the metal sheets to be inspected and x-rayed to confirm that no structural damage was caused by the welding of the nuts.
Additionally, this method of joining metal sheets is expensive. This is because of the man-hours and the many different tools—a keyplate, blank nuts, bull pins, welders, cutters, and grinders—it requires. Further, the tools are often damaged and have to be replaced after a few uses. That is especially true of the blank nuts which are welded into place and then cut free from the metal surface.
The typical method is also difficult to adjust once the process is started. Because the blank nuts are the anchor points for the process and because they are welded into place, if the blank nuts are not placed in the right location the very first time, the whole process has to be undone and started over at the beginning. This only adds to the time and expense of using this method.
Similarly cumbersome methods exist for joining large sheets of non-metallic materials like plastics and wood. Joining these materials is often done by laying the sheets on a work surface, such a floor or table. Then a weight is applied to the upper sheet to force it down to the lower sheet. At the same time, one or more workers must physically maneuver the sheets to achieve the desired alignment. If the sheets are joined in a vertical arrangement, then some form of backstop must be constructed to allow workers on one side of the material to push against the sheet. A common practice to accomplish this type of joinder of non-metallic materials is to create special tools and jigs each time a material must be joined.
These common methods for joining large sheets of non-metallic materials have several drawbacks. The construction of special jigs to join such materials is expensive and time consuming. These methods typically require the efforts of several employees, making them man-power intensive.